Monday 18 May 2009

Thinking outside the box again


The whole point with Dragonflying is that it should be simple and recapture some of the pioneer feel, so with that in mind I have been trying to assemble instrumentation for my Dragonfly without spending £200 plus on a Brauniger, Digifly (plus the speed probe at £70) or similar by thinking outside the box....thinking what pioneers would use.

They'd look to hang gliding, parachuting, camping, rock-climbing etc for equipment ideas...and after all, such areas of endeavour influenced Ben Ashman when he designed the Dragonfly: it doesn't have instruments, it uses lots of velcro for fixing, has a heavy duty carabiner for the back-up head gear, uses webbing straps, cycling pegs, rucksack snap-fasteners, etc.

So, yesterday I won an auction for a very small but practical altimeter, a Swiss made Thommen 15,000' with 3,000' on the first rotation, read easily, which is really all I would have needed, if there hadn't been inner scales. I am pretty sure from emailing the seller that it will adjust for QFE from QNH because after admitting that he didn't know how it works, he said:


"
The only knob is the outer casing (which could be turned while wearing gloves). This rotates the front "glass" which has a red line on, and the outer dial that shows the 0, 500, 1000, 1500, 2000, 2500 measurements (the red line points to the zero) ... this provides a reference point to the inner black pointer of the guage which will alter based on height/pressure.

That sounds just the job, doesn't it! I got it for £36, which together with a second hand stopwatch and the hang gliding ASI means that I have most of what I need, with a saving of a couple of hundred pounds, which can be spent on my radio.

If anyone is aware of a Microavionics headset, Icom A20 or A22 and a good interface, please let me know. Canny cheapskate has a little money waiting.

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